Turn singles and hazards are not working on my 2001 deville

Did you check the TSIG/HAZ fuse in the rear fuse block ? The rear fuse box is under the rear seat !
Could be a problem with the turn signal/hazard flasher module.
The TSIG/HAZ fuse in the rear fuse block supplies battery positive voltage to the turn signal/hazard flasher module. The turn signal/hazard flasher module has ground at G201. The turn signal lamps may only be activated with the ignition switch in the ON or START position. The IGN-1 fuse in the rear fuse block supplies battery positive voltage to the turn signal switch. When the turn signal switch is placed in either the left or right position, current flows from the turn signal switch assembly to the turn signal/hazard flasher module. The turn signal/hazard flasher module then sends an on-off voltage signal to either the left or right turn signals and their instrument cluster (IPC) indicator. When the hazard switch is pressed, the switch contacts are closed and the turn signal/hazard flasher module hazard input is grounded. In response to this input, the turn signal/hazard flasher module supplies battery positive voltage in an on and off flashing pattern to all the turn signal lamps. This also activates both turn signal indicators. When a THEFT is occurring, the Dash Integration Module (DIM) grounds the turn signal/hazard flasher module hazard input. The left turn signals have ground at G401and at G402. The right turn signals have ground at G401.

I would replace the turn signal hazard combo switch.